US6987662B2 - Multilayer ceramic capacitor - Google Patents

Multilayer ceramic capacitor Download PDF

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US6987662B2
US6987662B2 US11/043,267 US4326705A US6987662B2 US 6987662 B2 US6987662 B2 US 6987662B2 US 4326705 A US4326705 A US 4326705A US 6987662 B2 US6987662 B2 US 6987662B2
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dielectric
internal
layers
particles
internal electrode
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US20050180092A1 (en
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Takako Hibi
Kazunori Noguchi
Mari Miyauchi
Akira Sato
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TDK Corp
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TDK Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
    • A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
    • A61G5/10—Parts, details or accessories
    • A61G5/1056—Arrangements for adjusting the seat
    • A61G5/1064—Arrangements for adjusting the seat adjusting the depth of the seat
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
    • A61G2203/00—General characteristics of devices
    • A61G2203/10—General characteristics of devices characterised by specific control means, e.g. for adjustment or steering
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
    • A61G2203/00—General characteristics of devices
    • A61G2203/70—General characteristics of devices with special adaptations, e.g. for safety or comfort

Definitions

  • the present invention relates to a multilayer ceramic capacitor.
  • dielectric material for additives is added to internal electrode layer paste forming internal electrode layer in order to restrain breaking by firing, sintering of base metal conductive materials such as Ni, etc.
  • Dielectric material for additives added to the internal electrode layer paste is diffused to the internal dielectric layer during firing the non-fired capacitor device body. Therefore, as dielectric material for additives added to the internal electrode layer paste increases, diffusing ratio to internal dielectric layer during firing becomes higher.
  • Japanese Patent Publication (A) No. 2003-133164 discloses multilayer ceramic capacitor wherein the average particle size of dielectric particles near external electrodes is equal to or smaller to that of dielectric particles in the executive area.
  • the object of the technical as in Japanese Patent Publication (A) No. 2003-133164 is to prevent crack at external electrode when sintering.
  • An object of the present invention is to provide a multilayer ceramic capacitor wherein improvements in all kinds of electric characteristics, especially an improvement in TC bias characteristic while having sufficient dielectric constant can be expected even when the capacitor is made thinner.
  • multilayer ceramic capacitor having internal electrode layers, internal dielectric layers having thickness of less than 2 ⁇ m, and external dielectric layers are provided wherein,
  • Multilayer ceramic capacitor according to the invention can be manufactured such as by following procedures.
  • the manufacturing method of the multilayer ceramic capacitor of the invention is not limited to the following methods.
  • One of the above-mentioned methods is a manufacturing method of a multilayer ceramic capacitor comprising a step of firing multilayer body formed by using dielectric layer plate including dielectric material including main component material and subcomponent material, and internal electrode layer paste including dielectric material for additives wherein,
  • the other method is a manufacturing method of a multilayer ceramic capacitor comprising a step of firing multilayer body formed by using dielectric layer paste including dielectric material, including main component material and subcomponent material, and internal electrode layer paste including dielectric material for additives, wherein
  • dielectric material for additives include “at least main component material for additives”, and may further include subcomponent material for additives.
  • At least main component material for additives included in dielectric material for additives and main component material included in dielectric material in dielectric layer paste substantially may be the same composition group. Therefore, when dielectric material for additives include subcomponent material for additives other than main component material for additives, (1) only main component material for additives, a portion of dielectric material for additives, and main component material included in the dielectric material in dielectric layer paste have substantially the same composition group. In other words, the composition of subcomponent material for additives, the remainder of dielectric material for additives, and the composition of the subcomponent material included in dielectric material in dielectric layer paste may be different. (2) All of the dielectric material for additives (as a matter of course, main component material for additives is included) may have substantially the same composition group with all of dielectric material in dielectric layer paste.
  • dielectric layer merely expressed as “dielectric layer” signifies internal dielectric layer and/or external dielectric layer.
  • units of the average particle sizes D 50 a , D 50 b and D 50 c and the thickness x are considered to be all “ ⁇ m”.
  • the unit of existing ratio y 2 is considered to be “%”.
  • the inventors have found that, by restraining the particle growth of dielectric particles when firing and controlling microstructure inside the capacitor, all kinds of electric characteristics of obtained multilayer ceramic capacitor can be improved, specially, TC bias characteristic can be improved even with sufficient dielectric constant.
  • TC bias characteristic increases as the values in (1) and (2) approach the minimum value. More preferably, (1) and (2) are satisfied simultaneously. The most preferably, when the value of (1) is fixed, TC bias characteristic improves as the value of (2) decreases, in other words, as the coarse particles become few.
  • FIG. 1 is a schematic sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention
  • FIG. 2 is an enlarged sectional view of main portion of internal dielectric layer 2 as shown in FIG. 1 ;
  • FIG. 3 is an enlarged sectional view or main portion of external dielectric layer 20 as shown in FIG. 1 ;
  • FIG. 4 is a graph indicating each temperature change at removing binder treatment, firing, and annealing
  • FIG. 5 is a graph showing the relation of x and y 1 , wherein x is thickness of the internal dielectric layer 2 , and y 1 is ratio (D 50 a /D 50 b ) of D 50 a and D 50 b where D 50 a in an average particle size of dielectric particles 2 a included in the internal dielectric layers 2 and D 50 b is an average particle size of dielectric particles 20 a included in the external dielectric layer 20 and located at least 5 ⁇ m away from an internal electrode layer 3 a , arranged outermost part of all the internal electrode layers, to the stacked direction;
  • FIG. 6 in a graph showing the relation of x and y 2 , wherein x is thickness of the internal dielectric layer 2 , and y 2 is an existing ratio of dielectric particles (coarse particles), having the average particle size of at least 2.25 times larger than D 50 a , in the dielectric particles 2 a , where D 50 a is the average particle size of dielectric particles 2 a included in the internal dielectric layers 2 a and
  • FIG. 7 is a graph showing the relation of x and y 3 , wherein x is thickness of the internal dielectric layers 2 , and y 3 is a ratio (D 50 a /D 50 c ) of D 50 a and D 50 c where D 50 a is the average particle size of dielectric particles 2 a included in the internal dielectric layers 2 and D 50 c is the average particle size of BaTiO 3 material used to form internal dielectric layers 2 .
  • a multilayer ceramic capacitor having internal electrode layers, internal dielectric layers and external dielectric layers is exemplified to explain, wherein a plural number of the internal electrode layers and the internal dielectric layers are stacked alternately and external dielectric layers are arranged both end faces thereof to the stacked directions.
  • a multilayer ceramic capacitor 1 has a capacitor device body 10 of a configuration of internal dielectric layers 2 and internal electrode layers 3 stacked alternately. At the two ends of the capacitor device body 10 are formed a pair of external electrodes 4 conductive with each of the internal electrode layers 3 alternately arranged inside the device body 10 .
  • the internal electrode layers 3 are stacked so that end faces thereof alternately protrude out to the surfaces of the two opposing ends of the capacitor device body 10 .
  • the pair of external electrodes 4 are formed at the two ends of the capacitor device body 10 and are connected to the exposed end faces or the alternately arranged internal electrode layers 3 to form a capacitor circuit.
  • the shape of the capacitor device body 10 is not particularly limited, but normally is made a rectangular parallelepiped. Further, the dimensions are also not particularly limited and may be made suitable dimensions in accordance with the application. Usually, however, they are (0.4 to 5.6 mm) ⁇ (0.2 to 5.0 mm) ⁇ (0.2 to 1.9 mm) or so.
  • external electrode layers 20 are arranged at both outer ends of the laminating internal electrode layers 3 and internal dielectric layers 2 and providing protection to inside of the capacitor device body 10 .
  • “ 3 a ” as in the figures are an internal electrode layer arranged outermost part of all the stacked internal electrode layers.
  • compositions of internal dielectric layers 2 and the outer dielectric layers 20 are not particularly limited in the invention and it may be composed of the following dielectric ceramic composition.
  • the dielectric ceramic composition according to the present embodiment may include barium titanate as a main component.
  • Sub components, included with the main component in the dielectric ceramic composition include one or more from Mn, Cr, Si, Ca, Ba, Mg, V, W, Ta, Nb, R(R is Y, at least one kind of rare-earth element), Si oxide and compound becoming oxide by firing. Addition of the sub component allows to have capacitor characteristic even firing under reduced atmosphere. As impurities, at least around 0.1 weight % of trace components such as C, F, Li, Na, K, P, S, Cl may be included.
  • the compositions of the internal dielectric layers 2 nor the external dielectric layers 20 are not limited to the above composition.
  • the internal dielectric layers 2 nor the external dielectric layers 20 .
  • barium titanate is included and as sub component, magnesium oxide and yttrium oxide is included. Further, as the other sub component, at least one from barium oxide and calcium oxide and at least one from silicon oxide, manganese oxide, vanadium oxide and molybdenum oxide are included.
  • MgO is 0.1 to 3 mole
  • Y 2 O 3 is more than 0 mole to at most 5 mole
  • BaO+CaO is 0.5 to 12 mole
  • SiO 2 is 0.5 to 12 mole
  • MnO is more than 0 mole to at most 0.5 mole
  • V 2 O 5 is 0 to 0.3 mole
  • MoO 3 is 0 to 0.3 mole
  • V 2 O 5 +MoO 3 is more than 0 mole.
  • the number of laminated layers, thickness, and other conditions of the internal dielectric layers 2 may be suitably determined in accordance with the object or application.
  • the thickness x of internal dielectric layers 2 is made thinner to preferably less than 2 ⁇ m, more preferably, at most 1.5 ⁇ m.
  • the thickness of the external dielectric layer 20 is around 50 ⁇ m to several hundred micrometers or so.
  • internal dielectric layers 2 include dielectric particles 2 a and particle phase 2 c .
  • external electrode layers 20 include dielectric particles 20 a and the particle phase 20 c.
  • an average particle size of the dielectric particles 2 a included in the internal dielectric layers 20 is D 50 a
  • an average particle size of dielectric particles 20 a located at least 5 ⁇ m away from an internal electrode layers, arranged outermost part of all the internal electrode layers, to the stacked direction is 50 b
  • an average particle sizes of main component material used to form internal dielectric layer 2 is D 50 c .
  • the ratio of D 50 a and D 50 b (D 50 a /D 50 b ) is y 1 and the ratio of D 50 a and D 50 c (D 50 a /D 50 c ) is y 3 and ratio of the dielectric particles (coarse-grained particles) having 2.25 times larger average particle size than said D 50 a included in the internal dielectric layers 2 is y 2 .
  • the thickness of the internal dielectric layers 2 is X.
  • y 1 and x satisfy the following equations; y 1 ⁇ 0.75x+2.275 and y 1 ⁇ 0.75x+1.675.
  • y 1 is 0.7 to 1.3, preferably, 0.7 to 1.2.
  • y 1 is 0.85 to 1.45, preferably, 0.85 to 1.3.
  • y 2 and x satisfy the following equations; y 2 ⁇ 25x+37.5 and y 2 ⁇ 2.75x+4.125.
  • y 2 is 0.55 to 5, preferably, 0.55 to 3.5.
  • y 2 is 1.1 to 10, preferably, 1.1 to 8.5.
  • y 3 and x satisfy the following equations; y 3 ⁇ 0.95x+2.865 and y 3 ⁇ 0.95x+2.115.
  • y 3 is 0.88 to 1.63, preferably, 0.88 to 1.5.
  • y 3 is 1.07 to 1.82, preferably, 1.07 to 1.70.
  • D 50 a is preferably 0.05 to 0.5 ⁇ m, more preferably 0.05 to 0.4 ⁇ m.
  • D 50 a is too large, it will be difficult to make the layer thinner and that decline in electric characteristic such as TC bias can be observed, on the other, when D 50 a is too small, dielectric ratio decreases.
  • D 50 b is preferably the same with the above D 50 a.
  • D 50 a and D 50 b are defined as following. Capacitor device body 10 are cut in the stacked direction of dielectric layers 2 , 20 and the internal electrode layers 3 , and the average surface area of 200 or more dielectric particles 2 a at the cut face shown in FIG. 2 are measured, then, considering the surface areas as circles, diameter was calculated. “D 50 a ” is the value which was two and half times larger than the said diameter.
  • the average surface area of 200 or more dielectric particles 20 a at the cut face shown in FIG. 2 are measured, then, considering the surface areas as circles, diameter was calculated. “D 50 b ” is the value which was two and half times larger than the said diameter.
  • D 50 a is an average particle diameter of dielectric particles 2 a in internal dielectric layers 2 (portions contribute to capacitance) inserted between the internal electrodes 3 .
  • D 50 b is an average particle diameter of dielectric particles 20 a in external dielectric layers 20 (portions do not contribute to capacitance) not inserted between the internal electrode layers 3 .
  • Particle phase 2 c is normally composed of oxides of materials composing dielectric material or internal electrode materials, oxides of specially added materials or oxides of materials mixed as impurities during the process.
  • Internal electrode layers 3 as shown in the FIG. 1 is composed of base metal conductive materials that substantially act as electrodes.
  • the base metal used as conductive material Ni or an Ni alloy is preferable.
  • the Ni alloy an alloy of at least one element selected from Mn, Cr, Co, Al, Ru, Rh, Ta, Re, Os, Ir, Pt and W, and Ni is preferable.
  • the content of Ni in the alloy is preferably at least 95 wt %.
  • the Ni or Ni alloy may also include various trace components such as P, C, Nb, Fe, Cl, B, Li, Na, K, F, S in amounts of not more than 0.1 wt % or so.
  • the thickness of the internal electrode layers 3 are made thinner, preferably less than 2 ⁇ m, more preferably 1.5 ⁇ m or less.
  • external electrodes 4 as shown in FIG. 1 , normally at least one element from Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, Ir, or their alloys may be used. Normally, Cu, an Cu alloy, Ni, an Ni alloy, Ag, an Ag—Pd alloy, an In—Ga alloy are used.
  • the thickness of the external electrodes may be suitably determined in accordance with application etc., but normally is preferably 10 to 200 ⁇ m or so.
  • dielectric layer paste that composes internal dielectric layers 2 and external dielectric layers 20 as shown in FIG. 1 after firing and internal electrode layer paste composing internal electrode layers 3 as shown in FIG. 1 after firing are prepared.
  • Dielectric layer paste is prepared by mixing dielectric material and organic vehicle.
  • dielectric material is suitably selected from various compounds to be compound oxides or oxides by firing, such as carbonates, nitrates, hydroxides, organometallic compounds.
  • the dielectric material is normally used in powder form wherein the average particle size D 50 c is at most 0.5 ⁇ m, preferably around 0.05 to 0.4 ⁇ m.
  • D 50 c is a value calculated by converting the particles of material observed by SEM to a circle.
  • the organic vehicle includes a binder and a solvent.
  • the binder may be normal binders such as ethyl cellulose, polyvinyl butyral and acrylic resins.
  • the solvent used is not particularly limited and may be organic solvents such as terpineol, butyl carbitol, acetone, toluene, xylene and ethanol.
  • Dielectric layer paste can be formed by mixing dielectric material and vehicle wherein water-soluble binder is solved in water.
  • the water-soluble binder is not particularly limited but organic solvents such as polyvinyl alcohol, methyl cellulose, hydroxilic ethyl cellurose, water-soluble acrylic resin, emulsion etc.
  • the content of each component in dielectric layer paste is not particularly limited and, for instance, the dielectric layer paste can be prepared by including around 1 to 50 wt % of the solvent.
  • Additives suitably selected from all kinds of dispersant, plasticizers dielectric, sub component compounds, glass frit, insulators etc. may be included in the dielectric layer paste.
  • total content in the dielectric layer paste is preferably about 10 wt % or less.
  • the internal electrode layer paste is prepared by mixing conductive materials, dielectric material for an additive and organic vehicle.
  • the conductive materials Ni, Ni alloys and their mixtures are used.
  • the form of these conductive materials are not particularly limited and these may be spherical, flakes, etc. and mixture thereof.
  • the particle diameter of conductive material normally, when spherical, particles having an average particle diameter of less than 0.4 ⁇ m, preferably 0.01 to 0.2 ⁇ m or so is used. This is to realize highly advanced thinner layers.
  • the conductive material is included in the internal electrode layer paste preferably by 35 to 60 wt %.
  • Dielectric material for additives are effective in containing internal electrode (the conductive material) to sinter in firing process.
  • dielectric materials for additives include main component material for an additive and subcomponent material for an additive.
  • at least main component material for an additive included in dielectric materials for additives and main component material included in dielectric material in above dielectric layer paste substantially have the sane composition system. Therefore, only main component material for an additive, which is a component of the dielectric material for an additive, and the main material included in above dielectric layer paste may substantially have the same composition. And all of the dielectric material for additives and all of the dielectric material in dielectric layer paste may substantially have the same composition. In this way, at least making the compositions of main component material for additives and the main component the same, the composition in the dielectric layer 2 , 20 does not change by diffusion from internal electrode layers 3 to dielectric layers 2 , 20 .
  • main component material for additive in dielectric material for additive having specific lattice constant is preferably used.
  • main component material having specific lattice constant for additive improvement in all kinds of electric characteristics of the final obtained capacitor 1 can be attempted.
  • Lattice constant of main component material for additive in preferably over 4.000 and less than 4.057, more preferably 4.004 to 4.0475. There is a tendency that when the lattice constant is excessively small or excessively large, the improvement in all kinds of electric characteristics cannot be obtained.
  • main component material for additives in dielectric material for additive having specific discharge amount of hydroxyl group.
  • the discharge amount of hydroxyl group in main component material for additives is preferably 25 to 250, more preferably 25 to 150; There is a tendency that when the discharge amount of hydroxyl group is excessively small or excessively large, the improvement in all kinds of electric characteristics cannot be obtained.
  • An average particle size of main component material for additives can be the same with the particle diameter of main component material included in dielectric material in dielectric layer paste. Although, it is preferable to be more small and it is preferably 0.01 to 0.2 ⁇ m, more preferably 0.01 to 0.15 ⁇ m.
  • the value of average particle size is known to have interrelation with specific surface (SSA).
  • Dielectric material for an additive (It may only be main component material for additives or it may include both main component material for additives and subcomponent material for additives. The following is the same unless specially mentioned.) is not particularly limited but it is preferably produced through oxalate method, hydrothermal synthesis method, sol-gel method, hydrolysis method, alkoxide method etc. By utilizing the methods, the above mentioned dielectric material having the lattice constant and the discharge amount of hydroxyl group can effectively produced.
  • dielectric material for additives is included in the internal electrode layer paste preferably 10 to 30 wt %, more preferably 15 to 20 wt %.
  • the content of the dielectric material for additives is excessively small, the containing effect of sintering the conductive material lowers, and when excessively large, continuity of internal electrode lowers. Namely, when the dielectric material for additives is excessively small or large inconveniences may occur such that either of the case cannot maintain sufficient capacitance as a capacitor.
  • Organic vehicle contains binder and solvent.
  • Binder is such as ethyl cellulose, acrylic resins, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene or copolymer thereof are exemplified. Binder is included in the internal electrode layer paste, in comparison to mixed powders of conductive material and dielectric material for additives, is preferably 1 to 5 wt %. When the amount or binder is excessively small, the strength tends to decrease and when large, loading density of metals in the electrode pattern before firing tends to decrease and this may cause difficulty to maintain the smoothness in internal electrode layer 3 after firing.
  • solvent substances known in the art such as terpineol, dihydro terpineol, butyl carbitol, kerosene, etc. can all be used.
  • the content of the solvent is, in comparison to the entire paste, preferably around 20 to 50 wt %.
  • Plasticizer may be included in the internal electrode paste.
  • the solvent is exemplified by phthalate ester such as butyl benzyl phthalate(BBP), adipic acid, phosphorous acid, easter, glycol group etc.
  • green tip is prepared.
  • dielectric layer paste and internal electrode layer paste of prescribed pattern are printed and stacked on the carrier sheet; then, cut into prescribed form and exfoliated from the carrier sheet to prepare the green tip.
  • green sheet obtained by forming dielectric layer paste on the carrier sheet by prescribed thickness is formed, and internal electrode layer paste is printed on the green sheet by prescribed form, then the sheet is stacked to be green tip.
  • Process of removing the binder is, for instance, as shown in FIG. 4 , raising atmospheric temperature T 0 with prescribed rate of rise from room temperature (25° C.) to the holding temperature T 1 which removes binder, holding the temperature T 1 for prescribed time, then, reducing the temperature with prescribed rate of decline.
  • the rate of rise is preferably 5 to 300° C./hour, more preferably 10 to 100° C./hour.
  • Holding temperature T 1 when removing the binder is preferably 200 to 400° C., more preferably 220 to 380° C.
  • the holding time of T 1 is preferably 0.5 to 24 hours, more preferably 2 to 20 hours.
  • the rate of decline is preferably 5 to 300° C./hour, more preferably 10 to 100° C./hour.
  • Process atmosphere when removing binder is preferably air or reduced atmosphere.
  • Atmospheric gas when it reduced atmosphere is preferably moistened mixed gas of N 2 and H 2 .
  • Oxygen partial pressure under the reduced atmosphere it is preferably 10 ⁇ 45 to 10 5 Pa. When the oxygen partial pressure is excessively low, the effect of removing binder decreases and when excessively high, internal electrode layers tend to oxidize.
  • Process of firing the green tip is, for instance, as shown in FIG. 4 , raising atmospheric temperature T 0 with prescribed rate of rise from room temperature (25° C.) to the holding temperature for firing T 2 , holding the temperature T 2 for prescribed time, then, reducing the temperature with prescribed rate of decline.
  • the rate of rise is preferably 50 to 500° C./hour, more preferably 100 to 300° C./hour.
  • Holding temperature for firing T 2 is preferably 1100 to 1350° C., more preferably 1100 to 1300° C. and the most preferably 1150 to 1250° C.
  • the holding time T 2 is preferably 0.5 to 8 hours, more preferably 1 to 3 hours.
  • T 2 When T 2 is excessively low, even when the holding time of T 2 is made longer, densification becomes insufficient, and when excessively high, breakage of the electrode by abnormal sintering in internal electrode layer, deterioration of the capacity-temperature characteristics due to dispersion of the conductive materials forming the internal electrode layers; and reduction of the dielectric ceramic composition composing dielectric layer may tend to occur.
  • the rate of decline is preferably 50 to 500° C./hour, more preferably 200 to 300° C./hour.
  • Process atmosphere when firing is preferably reduced atmosphere.
  • Atmospheric gas when at reduced atmosphere is preferably moistened mixed gas of N 2 and H 2 .
  • the oxygen partial pressure under the firing atmosphere is preferably 6 ⁇ 10 ⁇ 9 to 10 ⁇ 4 Pa.
  • the oxygen partial pressure is excessively low, breakage of the electrode by abnormal sintering of conductive material in internal electrode layer may occur, and when excessively high, internal electrode layers tends to oxidize.
  • annealing is a treatment reoxidizing dielectric layer and that characteristics of the final capacitor is obtained.
  • Annealing process is, for instance, as shown in FIG. 4 , raising atmospheric temperature T 0 with prescribed rate of rime from room temperature (25° C.) to the holding temperature T 3 of annealing, holding the temperature T 3 for prescribed time, then, reducing the atmospheric temperature T 0 with prescribed rate of decline.
  • the rate of rise is preferably 100 to 300° C./hour, more preferably 150 to 250° C./hour.
  • Holding temperature T 3 of annealing is preferably 800 to 1100° C., more preferably 900 to 1100° C.
  • the holding time of T 3 is preferably 0 to 20 hours, more preferably 2 to 10 hours.
  • T 3 When T 3 is excessively low, oxidation of the dielectric layers 2 become insufficient, so the IR tends to become low or the IR lifetime tends to become shorter when T 3 is excessively high, not only are the internal electrode layers 3 oxidized and does the capacity fall, but also the internal electrode layers 3 end up reacting with the dielectric base material and deterioration of the capacity-temperature characteristic, a drop in the IR, and a drop in the IR lifetime tend to occur.
  • the rate of decline 18 preferably 50 to 500° C./hour, more preferably 100 to 300° C./hour.
  • Process atmosphere when annealing is preferably neutral atmosphere. Atmospheric gas when at neutral atmosphere is preferably moistened gas of N 2 . During the annealing, raising the temperature to the holding temperature T 3 under N 2 gas atmosphere, the atmosphere can be changed and the atmosphere through the annealing process can all be moistened gas of N 2 .
  • Oxygen partial pressure under the annealing atmosphere is preferably 2 ⁇ 10 ⁇ 4 to 1 Pa. When the oxygen partial pressure is excessively low, reoxidizing dielectric layer 2 become difficult and when high, the internal electrode layers 3 tend to oxidize.
  • the annealing may be consist of the raising temperature process and the declining temperature process. Namely, temperature holding time may be zero. In such case, the holding temperature T 3 is equivalent to the highest temperature.
  • the water temperature is preferably 0 to 75° C.
  • the treatment for removing the hinder, firing, and annealing may be performed consecutively or may be performed partially.
  • the above each treatment form the capacitor device body 10 composed of sintered body.
  • external electrodes 4 are formed onto the obtained capacitor device body 10 .
  • the formation of the external electrodes 4 can be performed by following processes that are known in the art.
  • the end faces of the obtained capacitor device body 10 composed of the mentioned sintered body is polished such as by barrel polishing or sand blasting, then, external electrode paste, usually including at least one element selected from Ni, Pd. Ag, Au, Cu, Pt, Rh, Ru, Ir etc. or their alloys, are baked or In—Ga alloys are applied onto both end faces. If necessary, the surfaces of the external electrodes 4 are plated to form covering layers.
  • treatment of removing binder, firing and annealing are performed separately.
  • at least 2 treatments can be done continuously.
  • atmosphere is changed without cooling, then, raising the temperature to the holding temperature T 2 for firing and the firing is performed, followed by cooling to the holding temperature T 3 of annealing and the annealing is performed.
  • Dielectric material was produced by preparing a plural kind of BaTiO 3 having average particle size D 50 c of 0.2 ⁇ m as main component, and for each BaTiO 3 , 0.2 mole % of MnCO 3 , 0.5 mole % of MgO, 0.3 mole % of V 2 O 5 , 2 mole % of Y 2 3 , 3 mole % of CaCO 3 , 3 mole % of BaCO 3 , 3 mole % of SiO 2 as subcomponent were prepared and wet mixed for 16 hours in the ball mill and dried.
  • dielectric layer paste 10 wt % of binder, 5 wt % of plasticizer, 150 wt % of solvent were weighed, mixed by ball mill, and slurrying was performed to obtain dielectric layer paste.
  • Ni particles having average particle size of 0.4 ⁇ m as conductive material, dielectric material for additives, ethyl cellulose resin as binder, and terpineol as solvent were prepared.
  • Dielectric material for additives including BaTiO 3 as main component material for additives which substantially has the same composition with dielectric material in said dielectric layer paste and subcomponent material for additives including MnCO 3 , MgO, V 2 O 5 , Y 2 CO 3 , CaCO 3 , BaCO 3 and SiO 2 .
  • the lattice constant of the main component material for additives in table 1 were calculated by the peak position obtained by XRD(rent 2000 made by Rigaku Corp.) at 300 mA, 50 Kv, 10 to 85 degrees which was considered as the lattice constant of tetragonal crystal.
  • the discharge amount of hydroxyl group in main component material for additives as in table 1 were calculated from peak intensity at 3510 cm ⁇ 1 caused by hydroxyl group expansion-oscillation by utilizing FT-IR (Fourier transform infrared spectroscopy) diffused reflection method.
  • FT-IR Fastier transform infrared spectroscopy
  • Multilayer Ceramic Tip Capacitor 1 as shown in FIG. 1 was prepared by utilizing the obtained dielectric layer paste and the internal electrode layer past as following.
  • Dielectric layer paste was applied onto the PET film by doctor blade method by prescribed thickness and then by drying them, 2 ⁇ m thickness of ceramic green sheet was formed.
  • the mentioned ceramic green sheets were considered to be the first green sheet and a plural number of the sheets were prepared.
  • the mentioned ceramic green sheets were considered to be the second green sheet and a plural number of the sheets were prepared.
  • Green sheet group was formed by laminating the first green sheets to the thickness of 300 ⁇ m. Then, 11 sheets of the second green sheets were stacked on the green sheet group. And further, on the second green sheets, the green sheet group was formed by laminating the first green sheets in the same way as mentioned above. Then, by heated at 80° C. and pressurized by 1 ton/cm 2 , green multilayer body was obtained.
  • the obtained multilayer body was cut to the size of 3.2 mm long ⁇ 1.6 mm wide ⁇ 1.0 mm height, removing binder treatment, firing and annealing under the below mentioned condition and then, the sintered body is obtained.
  • Graph showing each temperature change at removing binder treatment, firing and annealing is shown in FIG. 4 .
  • Removing binder was performed under the conditions of rising temperature rate of 30° C./hour, holding temperature T 1 of 250° C., holding time of 8 hours, falling temperature rate of 200° C./hour and treatment atmosphere of air atmosphere.
  • Firing was performed under the conditions of rising temperature rate of 200° C./hour, holding temperature T 2 of 1240° C., holding time of 2 hours, falling temperature rate of 200° C./hour and treatment atmosphere of reduced atmosphere(prepared by passing mixed gas of N 2 and H 2 through water vapor under oxygen partial pressure of 10 ⁇ 6 Pa).
  • Annealing was performed under the conditions of rising temperature rate of 200° C./hour, holding temperature T 3 of 1050° C., holding time of 2 hours, falling temperature rate of 200° C./hour and treatment atmosphere of reduced atmosphere(prepared by passing N 2 gas through water vapor under oxygen partial pressure of 0.1 Pa).
  • D 50 a (the average particle size of dielectric particles 2 a included in internal dielectric layer 2 ) was found by following procedures.
  • the obtained sintered body was cut and bladed at a plane perpendicular to the stacked direction of internal electrode layers, thermal etching treatment (1200° C., 10 minutes) was performed on the plane, particles of the plane were observed by SEM (scanning electron microscope), converting the particle area to circular area, and then diameter of the circle was made 1.5 times longer to be D 50 a.
  • D 50 b (the average particle size of dielectric particles 20 a included in external dielectric layer 20 ) was found by following procedures. Dielectric particles 20 a , included in the external dielectric layer 20 and located 5 ⁇ m away from the internal electrode layer 3 a , which is arranged outermost part of the internal electrodes 3 , to the stacked direction, was measured by the same procedure with the above D 50 a.
  • D 50 c (the average particle size of main component material used to form internal dielectric layer 2 ) was found by observing particles with SEM and converting particle areas to circular area.
  • TC bias was evaluated by following. Capacitor samples were evaluated in thermostatic chamber of 85° C. by LCR meter with 120 Hz, 0.5 Vrms, and bias voltage of 2 V/ ⁇ m. And the capacitance change rate was calculated from measured value at 20° C. and with bias voltage of no impression. As valuation basis, it was considered to be good when the capacitance change rate was more than ⁇ 23% when the thickness of dielectric layer was 1.3 ⁇ m, and more than ⁇ 25% when the thickness of dielectric layer was 1.1 ⁇ m.
  • Specific dielectric constant ⁇ was calculated from capacitance measured by digital LCR Meter (4274A made by YHP Co.) at the frequency of 1 kHz, an incoming signal level(measuring voltage) of 1.0Vrms (no unit). As valuation basis, it was considered to be good when the specific dielectric constant ⁇ was at least 1800 when the thickness of dielectric was 1.3 ⁇ m and at least 1700 when the thickness or dielectric was 1.1 ⁇ m, The results are shown in tables 1 and 2.
  • the correlation of x and y 1 is shown in FIG. 5
  • the correlation of x and y 2 is shown in FIG. 6
  • the correlation of x and y 3 is shown in FIG. 7 .
  • Capacitor samples were manufactured in the same way as example 1, except the thickness of internal dielectric layer 2 was varied to 2.0 ⁇ m and 2.2 ⁇ m and evaluated in the same way as example 1.

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US20060285274A1 (en) * 2005-05-31 2006-12-21 Tdk Corporation Multilayer electronic component and multilayer ceramic capacitor

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US8929054B2 (en) * 2010-07-21 2015-01-06 Cleanvolt Energy, Inc. Use of organic and organometallic high dielectric constant material for improved energy storage devices and associated methods
KR101872520B1 (ko) 2011-07-28 2018-06-29 삼성전기주식회사 적층 세라믹 전자부품
KR101771728B1 (ko) * 2012-07-20 2017-08-25 삼성전기주식회사 적층 세라믹 전자부품 및 이의 제조방법
JP2015026837A (ja) * 2013-10-30 2015-02-05 株式会社村田製作所 積層セラミック電子部品の製造方法及び積層セラミック電子部品
JP6525669B2 (ja) 2015-03-27 2019-06-05 Tdk株式会社 積層セラミック電子部品
JP2018037473A (ja) * 2016-08-30 2018-03-08 株式会社村田製作所 積層セラミックコンデンサ
KR102662851B1 (ko) * 2018-08-29 2024-05-03 삼성전기주식회사 적층 세라믹 커패시터 및 그 제조 방법
JP2022125694A (ja) * 2021-02-17 2022-08-29 株式会社村田製作所 積層セラミックコンデンサ

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US20060285274A1 (en) * 2005-05-31 2006-12-21 Tdk Corporation Multilayer electronic component and multilayer ceramic capacitor

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EP1560234A1 (en) 2005-08-03
USRE40665E1 (en) 2009-03-17
JP2005217304A (ja) 2005-08-11
US20050180092A1 (en) 2005-08-18
KR20050077769A (ko) 2005-08-03
TWI251241B (en) 2006-03-11
TW200534303A (en) 2005-10-16
KR100602004B1 (ko) 2006-07-18
JP4182007B2 (ja) 2008-11-19
CN1649048A (zh) 2005-08-03

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